1. Field of the Invention
The present invention relates to wheel assemblies and more particularly to a wheel assembly adapted for securing a deflated tire to the rim.
2. Prior Art
In most conventional wheel assemblies the inflated tire is secured in place by humps in the rim adjacent the inner surfaces of the tire beads, which, together with the air pressure, serve to hold the outer surfaces of the tire beads adjacent the rim flanges. Once a tire becomes deflated, however, severe sidewall deflection, such as occurs when a deflated tire is rolled against a surface as the vehicle is propelled, often forces the tire beads over the humps, thereby unseating the tire from the wheel and forcing the vehicle to be brought to a halt almost immediately after deflation of the tire occurs. Thus conventional wheel assemblies are incapable of securing a deflated tire on the rim over distances which normally must be traveled to get off a dangerous highway or out of a high crime area to a location where the tire may be safely changed. This inability to travel extended distances with a deflated tire also necessitates carrying a spare tire and the tools used to exchange the tire with the spare.
Various prior art attempts to resolve this problem have been offered. For example, U.S. Pat. No. 3,865,170 issued to Mitchell discloses a wheel assembly comprising a sealing ring disposed between a disc portion and a second rim part, these parts being held together by a nut and bolt assembly. The parts are so dimensioned that the ring protrudes above the bead seat of the rim adjacent the inner portion of the tire bead with the protrusion being of sufficient height to prevent the tire from becoming displaced even when the tire is deflated. Such an arrangement is not satisfactory however since it is expensive and leak prone, and requires that the wheel be disassembled and assembled each time the tire has to be changed. A similar arrangement with similar disadvantages is disclosed in U.S. Pat. No. 2,405,954 issued to Hollerith.
Another unsatisfactory prior art attempt at solving this problem is disclosed in U.S. Pat. No. 2,198,978 issued to Sauer, wherein either a ridge or a ring is disposed on the bead seat of the rim which serves the same purpose as the aforementioned sealing ring disclosed in U.S. Pat. No. 3,865,170. This arrangement is very similar to that employed on conventional wheel assemblies and does not satisfactorily secure a deflated tire on the rim.
Still another unsatisfactory prior art attempt at solving this problem is disclosed in U.S. Pat. No. 3,708,847 which discloses a wheel assembly in which the conventional well portion is replaced by a well portion disposed adjacent one of the rim flanges. In this arrangement, after the tire is mounted on the wheel, the wheel is disposed between a pair of guides which engage the sides of the well portion. These guides are moved together until the radially outer portions of the sides of the well are moved into contact with one another in such a way that the wheel then has a substantially continuous bead seat. A circumferentially extending hump may be formed in this bead seat to hold the tire beads more securely against axial forces, and, if desired, a hollow tube may be disposed in the well portion prior to compression. In such an instance, during compression the tube is forced radially outward so that it projects to form a circumferentially extending ridge adjacent the outboard bead of the tire. This may also be accomplished instead by use of a split metal ring. None of these approaches, however, is satisfactory in that once the well portion is subjected to compression, the profile of the rim is changed, with the result that the wheel cannot be reused. Thus tire replacement involves changing not only the tire, but also the entire wheel assembly as well.
These disadvantages of the prior art are overcome by the present invention.